Immense damage is caused worldwide as a result of the unauthorized use of computer programs. Solutions designed to protect computer programs against unauthorized use have been developed in order to counter this problem.
Transmitting encrypted information in order to activate a computer program serves to prevent unauthorized replications of the computer program. Moreover, corresponding methods serve for example as a technical precondition for selling computer programs as products via e-commerce. With previously known methods for activating computer programs, computer programs are enabled (activated) with the aid of a unique registration key in each case. In order to activate a computer program, the registration key which is permanently assigned to a computer program license is entered manually or loaded from a data medium. In particular with a plurality of computer programs installed on different computers, this results in a high administration overhead which is associated with labor-intensive operating and maintenance tasks.
A method wherein predefinable functions of a computer program can be activated for a selectable period of use by modification of a registration key pair is known from EP 1 191 419 A2. The registration key pair has at least one part-information item that is locked against user accesses. The functions which are to be activated do not necessarily have to have been already available for an activation at the time of an initial installation of the computer program, but can also be selected and added at some later time. No deployment of operating and maintenance personnel is necessary at the location of the computer on which the particular computer program is installed in order to activate the functions.
Components of the registration key pair according to the method described in EP 1 191 419 A2 are application information and an application value. The application information is input at a first computer on which the computer program to be registered is installed or, alternatively, is generated by the first computer. The application value is calculated from the application information by means of coding in a second computer.
For a registration of a computer program or a change to the registration, first application information comprising at least one partial information element that is locked against user accesses is transmitted to the second computer. In the second computer, an application value is calculated from the first application information and subsequently transmitted to the first computer. In the first computer, second application information is determined from the application value by means of decoding. The first and the second application information are checked to determine they match at the start of an execution of the computer program. Predefinable functions of the computer program are activated as a function of the differences resulting during the check.